**2. Drying techniques**

*Banana Nutrition - Function and Processing Kinetics*

Because bananas are highly perishable, there is a need for dehydration of banana to reduce postharvest losses. Among the useful processes used to preserve banana fruits are minimal processing [7–9], refrigeration [10, 11] and dehydration or drying [12–16]. Drying of banana is a useful method to reduce postharvest losses [17, 18] and to improve commercial value of banana. Drying has become necessary to make them available all year round and at locations where they are not produced. In addition to preservation, the reduced weight and bulk of dehydrated banana products decrease packaging, handling and transportation costs [17, 18]. Drying banana can also lead to quality changes such as physical, sensory, nutritional and microbiological. Omolola et al. [19] reported that drying banana gives rise to low or moderate glycemic index (GI) products with high calorie, vitamin and mineral

**Country Banana Plantain Total** India 29.1 29.1 China 13.1 13.1 Philippines 5.8 3.1 8.9 Ecuador 6.5 0.6 7.1 Indonesia 7.0 7.0 Brazil 6.8 6.8 Colombia 2.0 3.5 5.5 Cameroon 1.2 4.3 5.5 Uganda 0.6 3.7 4.3 Ghana 0.09 4.0 4.1 Guatemala 3.8 0.3 4.1 World 113.3 35.1 148.4

Drying is the process of moisture removal due to simultaneous heat and mass transfer under controlled conditions to reduce the bulkiness of the fruits [17, 18, 20–23]. It is one of the oldest methods of preservation and widely applied to banana fruits owing to its simplicity, ease of operation and cost-effectiveness. Besides these advantages, drying decreases the bulk of foods by reducing the volume which reduces packaging, handling and storage and transportation costs as well as ease of

Several researchers have carried out studies on drying of bananas, for example, solar drying [26], drying using vacuum [27], foam mat drying [28] and spray drying [29]. Dried banana is a food stock in ripe [30] or unripe maturation state [31]. The dehydration of banana results also in physical modifications as color change [32], shrinkage and porosity [33, 34] and texture [35, 36]. Based on their findings, important dehydration process variables that have influence on drying process and guarantee the obtainment of dried fruits with good quality have been done. Such parameters are appropriate cultivar, pretreatments and drying conditions [37–40]. A lot of research efforts are geared towards the study of drying kinetic of banana

fruits. The drying kinetics are usually used to predict the drying behaviour and for optimization of the drying parameters of various foods [41, 42]. Therefore, the chapter focuses on the existing and emerging drying techniques and drying kinetics

handling and processing operations [17, 18, 20–25].

**68**

of banana.

contents.

*Source: FAOSTAT [6].*

*2016 Production in millions of tonnes.*

**Table 1.**

Drying banana is the process of moisture removal due to simultaneous heat and mass transfer under controlled conditions [18, 42, 43]. Drying is the most energyintensive process in the food industry. Therefore, improving drying processes by reducing energy consumption, increasing efficiency of the drying process and providing high-quality products with minimal increase in economic input have become the goal of modern drying [44–46].

In drying of banana, convective drying in hot air is still the most popular method applied to reduce the moisture content of banana. However, the shortcomings of convective drying in hot air are very long drying period, high-energy consumption, contamination problems, low energy efficiency and high costs, which are not desirable for the food industry [47, 48]. But, the desire to reduce the above problems, as well as to achieve a fast and effective thermal process, led to the use of microwave and dielectric heating methods for banana drying [49, 50]. These drying methods have several advantages such as higher drying rate, shorter drying time, decreased energy consumption and better quality of the dried products when compared with the convective drying in hot air [51–53].

Drying methods are divided into natural and artificial methods of drying. The natural method of drying involves the use of energy from the sun to remove moisture from banana fruits. The major shortcoming of this method is that it depends on weather conditions and is highly inefficient [54]. Artificial method of drying uses mechanical devices to improve drying efficiency of the method [55]; this leads to products of better quality. In addition controlling of various factors involved in the drying process such as temperature, drying air flux and time of drying is also possible. Artificial drying is done with the help of mechanical or electrical equipment which improves efficiency.
